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HK: Physik der Hadronen und Kerne
HK 21: Theorie III
HK 21.5: Talk
Tuesday, March 20, 2001, 17:30–17:45, B
Chiral Dynamics of the Nuclear Matter Equation-of-State and Quark-Condensate — •Stefan Fritsch, Norbert Kaiser und Wolfram Weise — Physik-Department, Technische Universität München
We use chiral perturbation theory at finite baryon density to calculate the equation of state of nuclear matter. The loop-expansion transcribes itself into an expansion of the (binding)-energy per particle Ē(kf) in powers of the Fermi-momentum kf, modulo non-trivial functions of the ratio kf/mπ. We evaluate closed vacuum diagrams up to three-loop order which correspond to Ē(kf) ∼ kf6. We find that the irreducible chiral 2π-exchange contributions to Ē(kf) at order kf5 and kf6 are indeed of the size of the empirical binding energy Ē(kf(0))≃ −16 MeV at the saturation point kf(0)≃ 265 MeV. At lower orders in kf contributions arising from pion-exchange and four-nucleon contact interactions cancel each other. We regularize the few divergent parts of the two-pion exchange by a cutoff Λ and we estimate the strength of the contact interaction from ω-exchange. Differentiation of the resulting saturation curve Ē(kf,mπ) with respect to the pion mass allows us to calculate the deviations from the linear decrease in density of the chiral quark condensate in dense matter. We study the equation of state of pure neutron matter along the same lines. Supported in part by BMBF and GSI